1. Field of the Invention
The present invention is directed to novel delivery systems for psychotropic agents that ensure better patient compliance and therefore improved therapeutic efficacy and better overall mental health for the patient. More specifically, the present invention comprises injectable nanoparticulate olanzapine formulations having a prolonged duration of action.
2. Background of Invention
A. Background Regarding Olanzapine
Currently there are many drugs available for the treatment of disorders of the central nervous system. Among these drugs is a category known as antipsychotics for treating serious mental conditions such as schizophrenia and schizophreniform illness. The drugs available for such conditions are often associated with undesirable side effects, and there is a need for better products that control or eliminate the symptoms in a safer and more effective way. Furthermore, many patients do not respond or only partially respond to present drug treatment, and estimates of such partial-or non-responders vary between 40% and 80% of those treated.
Since antipsychotics were introduced it has been observed that patients are liable to suffer from drug-induced extra pyramidal symptoms, which include drug-induced Parkinsonism, acute dystonic reactions, akathisia, tardive dyskinesia, and tardive dystonia. The Simpson Angus Scale, Barnes Akathisia Rating Scale, and Abnormal Involuntary Movement Scale (AIMS) are well known scales for assessing extra pyramidal symptoms. The great majority of drugs available for treatment of schizophrenia are prone to produce these extra pyramidal side effects when used at dosages that yield a beneficial effect on the symptoms of the disease. The severity of adverse events and/or lack of efficacy in a considerable number of patients frequently result in poor compliance or termination of treatment.
Many of the drugs are associated with a sedative effect and may also have an undesirable influence on the affective symptoms of the disease, causing depression. In some instances long term use of the drug leads to irreversible conditions, such as the tardive dyskinesia and tardive dystonia referred to above. This, coupled with the fact that many of the patients in need of such drugs are not in full control of their mental faculties, often results in poor patient compliance and diminished therapeutic effect. A dosage form of such a drug having prolonged activity, and therefore requiring less frequent administrations, is highly desirable. This is because such a dosage form would minimize complications caused by patients missing or failing to take a dose.
A widely used and popular anti-psychotic drug useful in the treatment of disorders of the central nervous system is olanzapine, which is commercially available as Zyprexa® (Eli Lilly, Indianapolis, Ind.). Zyprexa® is available in both orally administered tablets and intramuscular injection formulations.
Olanzapine has the chemical name 2-methyl-4-(4-methyl-1-piperazinyl) -10H-thieno[2,3-b][1,5]benzodiazepine (C17H20N4S), a molecular weight of 312.439, and the following chemical structure:

Olanzapine is a yellow crystalline solid which is practically insoluble in water. The compound is disclosed and claimed in U.S. Pat. No. 5,229,382 to Chakrabarti et al., which is incorporated herein by reference.
Olanzapine is an antagonist of dopamine at D-1 and D-2 receptors, and in addition has antimuscarinic, anti-cholinergic properties, and is an antagonist for 5HT-2 receptor sites. The compound also has antagonist activity at noradrenergic alpha-receptors. These properties indicate that the compound is a potential neuroleptic with relaxant, anxiolytic, or anti-emetic properties, and is useful in treating psychotic conditions such as schizophrenia, schizophreniform diseases, and acute mania. At lower doses the compound is indicated for use in the treatment of mild anxiety states.
Olanzapine is a selective monoaminergic antagonist with high affinity binding to the following receptors serotonin 5HT2A/2C (KI=4 and 11 nM, respectively), dopamine D1-4 (KI=11-31I 25 nM), histamine HI(KI=7 nM), and adrenergic (alpha)1 receptors (KI=nM) GABAA, BZD, and (beta) adrenergic receptors (KI>10 μM).
The mechanism of action of olanzapine, as with other drugs having efficacy in schizophrenia is unknown. However, it has been proposed that this drug's efficacy in schrizophrenia is mediated through a combination of dopamine and serotonin type 2 (5HT2) antagonism. The mechanism of action of olanzapine in the treatment of acute manic episodes associated with Bipolar 1 Disorder is unknown.
Antagonism at receptor other than dopamine and 5HT2 with similar receptor affinities may explain some of the other therapeutic and side effect of olanzapine. Olanzapine's antagonism of muscorinic M1-5 receptors explains its anticholinergic effects. Olanzapine's antagonism of histamine H1 receptors may explain somnolence observed with this drug. Olanzapine's antagonism of adrenergic (alpha) receptors may explain orthostatic hypotension observed with this drug.
B. Background Regarding Nanoparticulate Drugs
Bioavailability is the degree to which a drug becomes available to the target tissue after administration. Many factors can affect bioavailability including the dosage form and various properties, e.g., dissolution rate of the drug. Poor bioavailability is a significant problem encountered in the development of pharmaceutical compositions, particularly those containing an active ingredient that is poorly soluble in water. Poorly water soluble drugs tend to be unsafe for intravenous administration techniques, which are used primarily in conjunction with fully soluble drug substances.
It is known that the rate of dissolution of a particulate drug can increase with increasing surface area, i.e., decreasing particle size. Consequently, methods of making finely divided drugs have been studied and efforts have been made to control the size and size range of drug particles in pharmaceutical compositions. U.S. Pat. No. 5,145,684 to Liversidge et. al., which is herein incorporated by reference, discloses particles of a drug substance having a non-crosslinked surface stabilizer absorbed on the surface thereof and methods for the preparation thereof. This patent does not teach or suggest nanoparticulate compositions of olanzapine.
Methods of making nanoparticulate compositions are described, for example, in U.S. Pat. Nos. 5,518,187 and 5,862,999, both for “Method of Grinding Pharmaceutical Substances;” U.S. Pat. No. 5,718,388, for “Continuous Method of Grinding Pharmaceutical Substances;” and U.S. Pat. No. 5,510,118 for “Process of Preparing Therapeutic Compositions Containing Nanoparticles.” These patents do not describe methods of making nanoparticulate olanzapine.
Nanoparticulate compositions are also described, for example, in U.S. Pat. Nos. 5,298,262 for “Use of Ionic Cloud Point Modifiers to Prevent Particle Aggregation During Sterilization;” U.S. Pat. No. 5,302,401 for “Method to Reduce Particle Size Growth During Lyophilization;” U.S. Pat. No. 5,336,507 for “Use of Charged Phospholipids to Reduce Nanoparticle Aggregation;” U.S. Pat. No. 5,340,564 for “Formulations Comprising Olin 10-G to Prevent Particle Aggregation and Increase Stability;” U.S. Pat. No. 5,346,702 for “Use of Non-Ionic Cloud Point Modifiers to Minimize Nanoparticulate Aggregation During Sterilization;” U.S. Pat. No. 5,352,459 for “Use of Purified Surface Modifiers to Prevent Particle Aggregation During Sterilization;” U.S. Pat. Nos. 5,399,363 and 5,494,683, both for “Surface Modified Anticancer Nanoparticles;” U.S. Pat. No. 5,429,824 for “Use of Tyloxapol as a Nanoparticulate Stabilizer;” U.S. Pat. No. 5,470,583 for “Method of Preparing Nanoparticle Compositions Containing Charged Phospholipids to Reduce Aggregation;” U.S. Pat. No. 5,518,738 for “Nanoparticulate NSAID Formulations;” U.S. Pat. No. 5,552,160 for “Surface Modified NSAID Nanoparticles;” U.S. Pat. No. 5,560,931 for “Formulations of Compounds as Nanoparticulate Dispersions in Digestible Oils or Fatty Acids;” U.S. Pat. No. 5,565,188 for “Polyalkylene Block Copolymers as Surface Modifiers for Nanoparticles;” U.S. Pat. No. 5,569,448 for “Sulfated Non-ionic Block Copolymer Surfactant as Stabilizer Coatings for Nanoparticle Compositions;” U.S. Pat. No. 5,571,536 for “Formulations of Compounds as Nanoparticulate Dispersions in Digestible Oils or Fatty Acids;” U.S. Pat. No. 5,573,783 for “Redispersible Nanoparticulate Film Matrices With Protective Overcoats;” U.S. Pat. No. 5,580,579 for “Site-specific Adhesion Within the GI Tract Using Nanoparticles Stabilized by High Molecular Weight, Linear Poly(ethylene Oxide) Polymers;” 5,585,108 for “Formulations of Oral Gastrointestinal Therapeutic Agents in Combination with Pharmaceutically Acceptable Clays;” U.S. Pat. No. 5,587,143 for “Butylene Oxide-Ethylene Oxide Block Copolymers Surfactants as Stabilizer Coatings for Nanoparticulate Compositions;” U.S. Pat. No. 5,591,456 for “Milled Naproxen with Hydroxypropyl Cellulose as Dispersion Stabilizer;” U.S. Pat. No. 5,622,938 for “Sugar Based Surfactant for Nanocrystals;” U.S. Pat. No. 5,718,919 for “Nanoparticles Containing the R(−)Enantiomer of Ibuprofen;” U.S. Pat. No. 5,747,001 for “Aerosols Containing Beclomethasone Nanoparticle Dispersions;” U.S. Pat. No. 5,834,025 for “Reduction of Intravenously Administered Nanoparticulate Formulation Induced Adverse Physiological Reactions;” U.S. Pat. No. 6,045,829 “Nanocrystalline Formulations of Human Immunodeficiency Virus (HIV) Protease Inhibitors Using Cellulosic Surface Stabilizers;” U.S. Pat. No. 6,068,858 for “Methods of Making Nanocrystalline Formulations of Human Immunodeficiency Virus (HIV) Protease Inhibitors Using Cellulosic Surface Stabilizers;” U.S. Pat. No. 6,153,225 for “Injectable Formulations of Nanoparticulate Naproxen;” U.S. Pat. No. 6,165,506 for “New Solid Dose Form of Nanoparticulate Naproxen;” U.S. Pat. No. 6,221,400 for “Methods of Treating Mammals Using Nanocrystalline Formulations of Human Immunodeficiency Virus (HIV) Protease Inhibitors;” U.S. Pat. No. 6,264,922 for “Nebulized Aerosols Containing Nanoparticle Dispersions;” U.S. Pat. No. 6,267,989 for “Methods for Preventing Crystal Growth and Particle Aggregation in Nanoparticle Compositions;” U.S. Pat. No. 6,270,806 for “Use of PEG-Derivatized Lipids as Surface Stabilizers for Nanoparticulate Compositions;” U.S. Pat. No. 6,316,029 for “Rapidly Disintegrating Solid Oral Dosage Form,” U.S. Pat. No. 6,375,986 for “Solid Dose Nanoparticulate Compositions Comprising a Synergistic Combination of a Polymeric Surface Stabilizer and Dioctyl Sodium Sulfosuccinate,” U.S. Pat. No. 6,428,814 for “Bioadhesive nanoparticulate compositions having cationic surface stabilizers;” U.S. Pat. No. 6,431,478 for “Small Scale Mill;” U.S. Pat. No. 6,432,381 for “Methods for Targeting Drug Delivery to the Upper and/or Lower Gastrointestinal Tract,” U.S. Pat. No. 6,592,903 for “Nanoparticulate Dispersions Comprising a Synergistic Combination of a Polymeric Surface Stabilizer and Dioctyl Sodium Sulfosuccinate,” U.S. Pat. No. 6,582,285 for “Apparatus for sanitary wet milling;” U.S. Pat. No. 6,656,504 for “Nanoparticulate Compositions Comprising Amorphous Cyclosporine;” U.S. Pat. No. 6,742,734 for “System and Method for Milling Materials;” U.S. Pat. No. 6,745,962 for “Small Scale Mill and Method Thereof;” U.S. Pat. No. 6,811,767 for “Liquid droplet aerosols of nanoparticulate drugs;” and U.S. Pat. No. 6,908,626 for “Compositions having a combination of immediate release and controlled release characteristics;” all of which are specifically incorporated by reference. In addition, U.S. Patent Application No. 20020012675 A1, published on Jan. 31, 2002, for “Controlled Release Nanoparticulate Compositions,” and WO 02/098565 for “System and Method for Milling Materials,” describe nanoparticulate active agent compositions, and are specifically incorporated by reference. None of these references describe nanoparticulate compositions of olanzapine.
Amorphous small particle compositions are described, for example, in U.S. Pat. Nos. 4,783,484 for “Particulate Composition and Use Thereof as Antimicrobial Agent;” U.S. Pat. No. 4,826,689 for “Method for Making Uniformly Sized Particles from Water-Insoluble Organic Compounds;” U.S. Pat. No. 4,997,454 for “Method for Making Uniformly-Sized Particles From Insoluble Compounds;” U.S. Pat. No. 5,741,522 for “Ultrasmall, Non-aggregated Porous Particles of Uniform Size for Entrapping Gas Bubbles Within and Methods;” and U.S. Pat. No. 5,776,496, for “Ultrasmall Porous Particles for Enhancing Ultrasound Back Scatter.” These references do not describe nanoparticulate olanzapine.
There is a need in the art for nanoparticulate olanzapine formulations which overcome these and other problems associated with prior conventional olanzapine formulations. The present invention satisfies these needs.